Full face mask for a PAPR

ABSTRACT

A full face mask ( 1 ) for a PAPR (Powered Air Purifying Respirator) to be used in health hazardous environments, having an air inlet ( 7, 8 ) and an air outlet ( 16 ), manufactured in one piece from a transparent plastic in a one step vacuum forming process with a single curved field of vision ( 4 ) exempt from distorsions and comprising a compartment ( 5 ) inside a forehead area of the full face mask for accommodating a blower unit ( 2 ).

TECHNICAL FIELD

The present invention relates to PAPRs (Powered Air PurifyingRespirator), and more specifically a full face mask for PAPRs to be usedin health hazardous environments, such as scenes of fire, constructionsites, virus containing environments and the like.

BACKGROUND

For personal protection, hand washing is of course essential, but forhealth care personal and others subjected to virus containingenvironments, there are masks and respirators. Facemasks or surgicalmasks are mostly loose fitting disposable masks stopping droplets andskin or hair particles, and prevent splashes from contacting the face ofthe wearer, but they are no good for virus protection e.g. because ofsealing problems against the face, and a negative pressure inside themask during inhalation. Respirators, and in this context air-purifyingrespirators are air filtering devices that protect against inhalation ofboth large and small particles by removing contaminants by filtration orabsorption. They may be passive, APR, or powered, PAPR.

The PAPRs of today have a great advantage over APRs, because they onlyrequire a simple fit test, and they do not increase the work ofbreathing. However, because of growth of beard, wrinkles etc. it isdifficult to obtain a perfect sealing against the face. These problemsare set aside by providing a positive pressure inside the face mask.However, there are also a number of disadvantages with today's PAPRs,they require special training to put on, to use safely and to take off;fan noise impedes conversation; it is difficult to use a stethoscope.They may cause claustrophobia.

Made of thick rubber or other sound restricting material, they makeconversation difficult and therefore require special amplifiers orspeech diaphragms, and telephone conversation is virtually impossible.

Another great disadvantage is that it is very difficult to see were youput your feet because of the restricted field of vision when lookingdown, especially when remounting a staircase.

Still another disadvantage is that the weight of existing PAPRs isconsiderable, causing a lot of strain on the neck, and they aretherefore quit uncomfortable for a normal human being, such as nurses,doctors, etc.

Therefore, there is a great need of improvements of existing PAPRs. Alsoin other areas there is always a need for comfortable easy-to-use safetyequipment with improved performance.

THE INVENTION

One object of the invention is to provide a full face mask for a PAPRwhich is easy to use and comfortable to wear, and does not interferewith the use of other equipment.

Another object of the invention is to provide a method for themanufacture of a full face mask for a PAPR with a perfectly clear fieldof vision.

A further object of the invention is to provide a disposable full facemask for a PAPR.

A further object of the invention is to provide a blower unit givingrise to a minimum of fan noise and with the ability to control thepressure inside a full face mask, and preferably to maintain a positivepressure inside the mask.

A further object of the invention is to provide a full face mask for aPAPR capable of housing a blower unit inside the full face mask to beprotected from the environment and eliminating ducting and flow losses,and being reusable with its own rechargeable battery but with the optionto use an external battery connected through a wire.

A further object of the invention is to provide a full face mask withintegrated filter, preferably an electrostatic filter for minimizing theflow resistance.

These and other objects of the invention are attained with the PAPRaccording to the present invention as it is defined in claim 1.

Preferred embodiments and developments of the invention are made theobject of sub claims.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained more in detail in the followingdescription of embodiments of the invention shown in the drawings, onwhich

FIG. 1 shows schematically an exploded view of the PAPR according to theinvention,

FIG. 2 shows schematically a view from behind of the face mask with theblower unit separated from the face mask,

FIG. 3 shows a view corresponding to FIG. 2 with the blower unitinstalled in the face mask,

FIG. 4 shows a schematic exploded view of the blower unit in enlargedscale,

FIG. 5 shows an alternative embodiment of a gasket for the full facemask comprising an inner mask,

FIG. 6 shows a further embodiment of the face mask according to theinvention with integrated sealing rim and with a separate harness,

FIG. 6a shows a cross sectional view of the integrated rim in anenlarged scale, and

FIG. 7 shows a view corresponding to FIG. 6 with the full face maskinserted in the harness

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 a schematic exploded view of a PAPR incorporating oneembodiment of the full face mask according to the invention. The fullface mask 1 is shown to the right and a blower unit 2 to the left.According to this embodiment a face seal 3 is provided for sealing offthe interior of the full face mask against the face.

The full face mask 1 is manufactured in one piece preferably from PET(polyethylene terephtalate) by vacuum forming. Although PET is apreferred plastic material because of its properties, other plasticmaterials can be used as well. The field of vision 4 is a single curvedsurface, the foremost part of which is indicated with a line 4 a.

According to the invention, the field of vision is clear and devoid ofany distorted areas, which is accomplished by manufacturing the fullface mask from a transparent plastic in one piece in a vacuum formingprocess, in which method a plastic film or sheet is heated, while heatis prevented from reaching an area corresponding to a field of vision ofthe full face mask. During the vacuum forming process the field ofvision is given a single curved form by suction towards a formingsurface, and when the heated parts of the plastic after being vacuumformed have cooled, they will maintain the desired form of the field ofvision, which will be perfectly clear with a perfect visibility withoutany distortions.

In the forehead area there is a compartment 5 for accommodating theblower unit 2, which compartment is open towards the interior of theface mask as is clearly shown in FIG. 2. This compartment 5 forms aprotrusion, with an upper wall 6 extending substantially perpendicularto the face mask. In the upper wall of the compartment two openings 7,8, FIG. 1, are arranged, the function of which will be explained below.Further, the upper wall is designed with a rim 9. A filter unit isformed with an outer wall element 10 to be bonded to said rim. In theresulting chamber a filter element 11 is be encased. Between the filterand the upper wall of the blower unit compartment is arranged a support12 for the filter acting as a spacer. A valve seat 13 can be integratedwith the support, as is illustrated in FIG. 1.

At present, the placement of the blower unit in a chamber in theforehead area of the full face mask is preferred, but as is obvious, acompartment for the blower unit could be place in another part of thefull face mask.

The outer wall element 10 has air inlet openings 14, which should bedesigned to prevent entrance of contaminants into the filtercompartment. For example, it might be necessary to shower when wearingthe face mask, or if used outside it might be raining.

The filter element 11 is preferably an electrostatic filter, which has alow flow resistance. A suitable electrostatic filter material is MESfrom Munktell Filter AB, Sweden. However, the filter element can also bea HEPA filter, a carbon filter or any combination of electrostaticfilter, HEPA filter and carbon filter.

According to one embodiment of the invention a one-way valve is arrangedin the opening 7 between blower unit compartment and filter unit with aflexible diaphragm 15, made of e.g. rubber or a material havingproperties corresponding to rubber. This is a reliable and inexpensivesolution. If a more linear action is desired a valve working with aspring loaded sealing member can be used.

In the area of the face mask in the vicinity of the mouth the air outlet16 is arranged. In the illustrated embodiment an exhalation valve isarranged in the air outlet in the form of a one-way valve having a valveseat 17 and a flexible or spring-loaded diaphragm 18 opening duringexhalation, and closing during inhalation. A housing 19 is arranged onthe outside of the valve, with air outlet openings. The volume of thehousing should be sufficient to create a volume of exhalation airoutside the valve which will prevent surrounding air from entering thevalve during the time it takes for it to close when a person using thePAPR stops exhaling and begins inhaling.

The sealing 3 sealing the full face mask 1 against the face of a weareris preferably also vacuum formed in one piece. It is then cut or stampedto have a central opening 20 adapted to the full face mask. The sealingis designed with a form adapted to the form of the face mask having arim 21 lying adjacent to the inner sides of the full face mask, and alsohaving a fold 22 in order to abut the rim 23 of the full face maskthereby creating double sealing surfaces against the face of the wearer.The sealing is preferably made of polyethylene.

Flaps 24 are arranged around the perimeter of the face mask forstrapping the face mask over the face with the straps meeting at theback of a wearer's head. As is conventional, a wearer will be able toadjust the straps so that the face mask feels comfortable to wear whileat the same time a sufficient pressure is exerted on the sealing toobtain the sealing effect between the interior of the full face mask andthe surroundings. Other arrangements are of course also possible.

In FIG. 2 a gasket 25 is arranged around the openings in the upper wallof the compartment 5 for sealing against the blower unit 2 and theblower unit is shown in its assembled state. A snap hook element 26 isarranged at one end of the blower unit facing a wearer, which detachablylocks the blower unit in the face mask in a corresponding seat 27 in theface mask. The extension of the snap hook element is adapted so that,when the blower unit is locked in the full face mask, a sufficientpressure is exerted on the gasket 25 to obtain a desired sealing effectaround the openings in the upper wall of the blower unit compartment.

FIG. 3 illustrates the blower unit 2 installed in its compartment 5 inthe full face mask and with the face mask sealing 3 preferablypermanently bonded to the face mask.

In FIG. 4 an exploded view of the blower unit according to the inventionis shown. It comprises a housing with a lower part 28 and an upper part29. Electronic components are arranged on a printed circuit card 30,which, when the blower unit is assembled, will lie in the middle of thehousing formed by the lower and upper part of the housing, creating twocompartments.

In the lower compartment 31 underneath the printed circuit card there isspace for a rechargeable battery, and also for further operativefunctions. As is schematically shown in the front end of the lowerhousing part a diaphragm push button 32 is arranged in the wall as wellas contact elements 33 to be connected to the printed circuit card. Suchpush buttons can be operated by pressing them through the lower blowerunit compartment wall of the face mask. In a preferred embodiment of theinvention, one push button operate the start/stop function of the blowermotor, another push button operates a LED light arranged at the frontend of the blower unit. Further, although not shown in FIG. 4. LEDindicator lamps are preferably arranged in the lower wall of the housingfor indicating e.g. that the blower is running, the remaining capacityof the rechargeable battery, that a predetermined pressure prevails inthe face mask, etc. Further, a connector for connection of an externalbattery through a wire can be arranged in a compartment wall, making itpossible to change batteries without taking of the face mask.

In the upper part of the housing, the functional parts of the blowerunit are arranged. The electronic circuits being known per se will notbe described in detail. A battery powered motor 34 drives a fan wheel35. In the embodiment shown on the drawings the fan wheel has an axialinlet 36 and radial outlets 37, but other designs are also possible.Filtered air is drawn by the fan wheel through an opening 38 in theupper part of the blower unit housing and through the opening in theupper wall of the blower unit compartment from the filter unit.

In order to maintain a predetermined overpressure inside the full facemask the blower unit comprises a differential pressure gauge. In theembodiment illustrated in the FIGS. 1 and 4, a differential pressuresensor 39 with a flexible diaphragm 40 is used together with acombination 41 of an IR light emitter and a reflected IR light receiverfor IR light reflected from the surface of diaphragm. The sensorcomprises said flexible diaphragm 40 arranged at a distance above theprinted circuit card 30 defined by a spacer 42 and a cover 43 beingfastened to the printed circuit card and having a channel 44communicating with the ambient through the filter unit via a separateopening 8, FIG. 1, in the upper wall of the blower unit compartment 5.The diaphragm 40 has a diameter exceeding the diameter defined by thespacer or a seat for the diaphragm in the spacer or in the cover, andwith a free space underneath and above the diaphragm.

When the pressure outside the filter unit exceeds the pressure in thefull face mask the diaphragm will “flap” downwards, and when thepressure in the full face mask exceeds the pressure outside the filterunit the diaphragm will “flap” upwards. The sensor sensing the reflectedIR light will react and signals will be sent to a microprocessor on theprinted circuit card, which with appropriate circuitry will regulate theblower motor accordingly to maintain a desired overpressure in the fullface mask.

The motor 34 is a small motor with sensors controlled by amicroprocessor. The microprocessor also receives signals regarding forexample pressure and battery charge level. Based on data signalsreceived, the microprocessor sends out audible and/or visual warningsignals and instructions for the operation of the motor.

In FIG. 5, a further embodiment of the full face mask sealing isillustrated. The sealing 50 has an integral part 51 forming an innermask sealing off an upper volume in the full face mask from a lowervolume. A front edge 52 of the part 51 sealingly abuts the inner surfaceof the full face mask above the air outlet of the full face mask. Asillustrated in FIG. 5 the upper and lower volumes communicate throughopenings 53, 54. One-way valves may be arranged in said openings. In analternative embodiment a front edge 52 is made flexible in order to sealagainst the inner surface of the full face mask during exhalation, andopen during inhalation.

The purpose of the inner mask is to reduce the exhalation air volume andprevent build up of CO₂ inside the full face mask in case the blowerunit stops working. At the same time this allows the use of the fullface mask in APR mode, i.e. as an Air Purifying Respirator.

In order to make the full face mask for a PAPR according to theinvention more flexible, it is possible to provide the an inner mask,and in case the inner mask is not wanted, it can be removed. In order tosimplify this option, weakening lines can be arranged as is illustratedin FIG. 5 with a dotted line 55 in the areas, where the inner mask isconnected to the full face mask sealing 50.

A second embodiment of the full face mask according to the invention isschematically illustrated. Only the differences between this embodimentand the embodiment according to FIGS. 1-5 will be discussed.

The full face mask 60 differs from the full face mask according to theprevious embodiment in that it is designed with an integrated sealingrim 61. This rim 61 also forms a seating for a harness 62 comprising aclosed band element 63 adapted to fit snugly around the perimeter of thefull face mask and to abut the rim 61 thereof. Straps 64 fastened in theband element 63 have the function to tighten the full face mask againstthe face of a wearer.

A suitable embodiment to the sealing rim 61 of the full face mask isillustrated in FIG. 6a . The rim is formed with folds 65 and a free endpart 66 approximately perpendicular to the extension of the adjacentpart of the full face mask. With this embodiment the sealing rim willact as a bellows which adjusts to the face of a wearer, indicated at 67.

The rim can of course be designed in different forms giving the sameeffect, but as shown, it should be resilient, and of course, it shouldbe possible to produce the full face mask in a one step vacuum formingprocess inclusive of the rim.

In FIG. 7 the full face mask 60 is shown inserted in the harness 62.

One great advantage with the embodiment according to FIGS. 6 and 7 isthat the full face mask is produced in one piece, and no extra sealingmeans is needed. The harness can be reused when the face mask needs tobe discarded.

The invention claimed is:
 1. A disposable full face mask for a PAPR(Powered Air Purifying Respirator) to be used in health hazardousenvironments, having an air inlet and an air outlet, said full face maskbeing manufactured in one piece from a transparent plastic in a one-stepvacuum forming process with a transparent visor having a single curvedfield of vision exempt from distortions, wherein said full face maskcomprises a filter unit as an integral part of the full face mask, acompartment inside the full face mask for accommodating a blower unitinside the full face mask for maintaining a positive pressure inside themask, said compartment and the blower unit accommodated therein beingsituated between the transparent visor and the forehead area of a userof the full face mask and being open towards an interior of the fullface mask, wherein said blower unit is protected from the environment bysaid filter unit, and wherein said blower unit is detachably connectedto the compartment so as to enable reuse of the blower unit when thefull face mask is disposed of, and a face sealing being a separate piecebonded to the full face mask, said face sealing comprises an integralpart forming an inner mask sealing off an upper volume in the full facemask from a lower volume in the full face mask, wherein said facesealing further comprises a rim and a fold abutting the rim to createdouble sealing surfaces for sealing said full face mask against theforehead and face of the user.
 2. The disposable full face maskaccording to claim 1, wherein the filter unit comprises an electrostaticfilter, a HEPA filter, a carbon filter or any combination thereof. 3.The disposable full face mask according to claim 1, wherein the fullface mask is manufactured from PET.
 4. The disposable full face maskaccording to claim 1, wherein said inner mask has air inlet openings. 5.The disposable full face mask according to claim 4, wherein one-wayvalves are arranged in said openings.
 6. The disposable full face maskaccording to claim 1, wherein said inner mask sealingly engages with aninside of the full face mask at exhalation, but allows air to pass whena pressure above said inner mask exceeds the pressure below said innermask.
 7. The disposable full face mask according to claim 1, whereinsaid full face mask comprises an integrated resilient sealing rim formedin said one step vacuum forming process.
 8. A PAPR comprising thedisposable full face mask according to claim
 1. 9. The PAPR according toclaim 8, wherein a one-way valve is arranged in said air outlet with ahousing surrounding said air outlet on the outside of said disposablefull face mask enclosing a volume sufficient to prevent surrounding airto enter the face mask before the valve closes at inhalation.
 10. ThePAPR according to claim 8, wherein a one-way valve is arranged in theair inlet.
 11. The PAPR according to claim 8, wherein the disposablefull face mask includes an integrated sealing rim formed in saidone-step vacuum forming process, and a harness adapted to be removablyfitted around the disposable full face mask and to abut said rim whenthe full face mask and the harness are assembled.
 12. The PAPR accordingto claim 8, wherein the blower unit comprises a differential pressuresensor.
 13. The PAPR according to claim 12, wherein said differentialpressure sensor comprises an IR light emitter, a reflected IR lightreceiver, and an IR light reflecting surface reactive to a pressuredifference between the outside and the inside of the full face mask. 14.The PAPR according to claim 13, wherein said IR light reflecting surfaceis the surface of a flexible diaphragm arranged in the blower unit andcommunicating on one side with ambient pressure and on the other sidewith the pressure prevailing inside the full face mask.